DE4232120A1 - SYSTEM FOR INTERFACE CONNECTION OF TELEPHONE SETS WITH A CENTREX SYSTEM - Google Patents

Description

Field of the Invention

The present invention relates to telephone systems and, more particularly, to a system for Centrex services and upscale services for telephone sets and telephone devices to provide, which would otherwise not be able, in an appropriate manner via an interface with a Centrex system (centralized PABX = central private branch exchange) may be connected or perform certain Centrex services.  

Background of the Invention

A Centrex system, which is connected to a central office, has long been known for that it provides PABX and other features to the participants. Typically you have one separate subscriber line from the Centrex system to each telephone or telephone set. This offers the possibility of non-blocking. To use the Centrex system are special Telephone equipment or apparatus required for the specialized centrex line or control signals and which special control signals to the Centrex system can transmit. Such special telephone sets are therefore expensive.

When a group of participants would like to have fewer features or performance functions or more features than those provided by the Centrex system, but nevertheless wanted to use the centrex system, this was practically not feasible since it it is expensive to provide different (performance) levels of the Centrex phone and it is has not previously been possible to provide Centrex lines with service properties, that go beyond those that can be provided by the Centrex system.

Summary of the present invention

According to the present invention is a system for interfacing phone sets provided with a Centrex system, this linking or interface system always has access to the Centrex system. There is preferably a selected centrex line for each telephone set and therefore there is no blocking in the interface system. The present However, the invention provides devices for operating a number of different ones Telephone sets that have functionalities beyond those provided by the Centrex system Features go beyond or have lower capabilities, and these additional Features can be handled by the present invention and the services can be provided by the present invention.

The possibilities of the present invention can be changed or defined under Use of an insertable ROM cassette (read only memory cassette), which the The ability of the present invention controls to operate certain telephone sets. For example, the present invention can be used via an interface Feature level or ability level to interconnect different digital phone sets, which to Examples are available from Mitel Corporation, for example those that have displays that have no displays, those that have softkeys (input keys) (with different Functions that are shown on a display), etc.  

As a result, the present invention provides increased flexibility for the user and considerably reduced costs because special expensive Centrex telephone sets are not used and the level of skills or characteristics of centrex services can be accessed or changed to a level requested by the customer, without resorting to the telephone company.

In addition, the present invention allows inexpensive tip and ring 2500 lines can be used between the present invention and the Centrex system and that nevertheless phone sets with great possibilities can be used because of the inter pretationsfunktion for various control or line signals, by the present Invention is provided.

The loop length of the present invention to the centrex system can be, for example, 4 to 5 km and an additional loop length from the present invention to the telephone set can also be 2 to 3 km. So there can be an increased loop length over that of the normal centrex lines can be used. Normal centrex lines have one limited loop length of, for example, 2 to 3 km due to the special line inter faces on the Centrex and on the special Centrex telephone sets and the (special) Lines with a high feature potential are required. The present invention extends thus the radius around the centrex system in which the centrex services are provided can be. According to the present invention, there is a system for the interface servers linking of telephone sets with a Centrex system of peripheral circuits for the Interface formation for telephone lines which are connected to telephone sets and for which Formation of interfaces for Centrex lines, with a handling unit for the set with the peripheral circuits is connected to individual telephone lines and individual To connect Centrex lines together, and the handling unit for the set one Device for translating line and / or control signals, which of the Telephone sets are received in line and control signals of a type different from that Centrex system can be recognized, whereby a Centrex call progresses or is carried out as provided by the Centrex system.

Each telephone set is preferably assigned to a selected centrex line and can be used for connected on a 1: 1 basis (in a clear assignment).

The handling unit for the set can consist of a device for translating line and / or control signals which are received by the telephone sets, and around  To provide services for the telephone sets that respond to (to the signals) in addition to the (services or functional features) or instead of these.

The present invention preferably consists of a device for translating line and / or control signals received by the Centrex system and to, under Responsive to providing services or features for the phone sets that otherwise could not be handled by the phone sets.

The present invention can consist of a device for translating line and / or Control signals exist which are received by the Centrex system and to, under Responsive to providing services for the phone sets in addition to those provided by the Centrex system, or in place of them are.

Brief description of the figures

A better understanding of the present invention can be had with reference to the following detailed description in conjunction with the following drawings, wherein

Figure 1 is a basic block diagram of the invention and

Figure 2 is a somewhat more detailed block diagram of the invention.

Detailed description of the invention

Reference is now made to FIG. 1, in which a centrex system 1 is shown, which has different push and ring lines 3 (tip and ring lines), one of which is intended for use with an individual telephone set. These lines end in an interface 5 . Subscriber lines 7 connect the interface to corresponding telephone sets 9 . A ROM 11 (read only memory) is preferably plugged into the interface 5 in order to determine the characteristic level or the types of service functions which are to be provided by the interface 5 .

During operation or use, a telephone set 9 or a telephone is removed (pick up the handset). The closing of the hook switch, which is linked to the unhooked state, is detected in the interface 5 and a corresponding hook switch connection, which is on a line 3 which belongs to this telephone or telephone set, is transmitted to the Centrex system 1 (appears on the line 3 ) from the interface 5 and is detected in the Centrex 1 . The subscriber line is connected to the Centrex line 3 . Conversely, the Centrex 1 transmits the dial tone (the dial tone) on this line 3 , which is passed through the interface 5 to the telephone set 9 , which is unhooked (switched to a line connection).

The subscriber who belongs to this telephone set with the handset picked up, for example, now dials a seven-digit number which is routed through the Centrex 1 . The interface 5 also monitors any signaling from the telephone set 9 which is not a standard for the Centrex or Centrex system. For example, the Centrex typically provides a stop signal, a conference call, or other services that are signaled directly from the telephone set 9 . However, if the telephone set 9 provides a signal which is not standard for the Centrex 1 , the interface 5 detects it and replaces it with the signal which is expected from the Centrex 1 . This often occurs when the phone set is not a special Centrex device or set.

Furthermore, the interface 5 can provide services that are not normally provided by the Centrex 1 , for example the ability for a local call or guest call, the operation of softkeys (selectable or programmable keys), including the labeling or naming of certain push buttons the telephone sets on an associated display, etc. When a telephone set (telephone set) generates command signals to call up such services, either automatically or based on a service request signal resulting from the pressing of a special or predetermined push button on the telephone set, the interface 5 can do so Block signals on the route to the Centrex 1 and provide the service, for example by transmitting control signals to the telephone set 9 and the Centrex system. If, for example, a local call is to be made or called up, the interface should transmit a stop signal to the Centrex, which causes the Centrex system to give a stop signal on line 3 and then it should connect the subscriber's handset to a local call amplifier.

The services that can be provided for the subscribers can be defined and / or programmed in a plug-in memory module ROM 11 which controls which translation properties and which level of service can be provided. If it is known, for example, that the telephone devices 9 have no displays, the ROM 11 controls the interface 5 so that display control signals, for example relating to the display call or the called line numbers, or the softkey designations, are not generated and are not transmitted to the telephone devices neither from the Centrex system nor from the interface.

FIG. 2 clearly illustrates a block diagram of the invention. Each of the centrex lines 3 and the subscriber lines 7 ends at a suitable line circuit, which is designated as PIC (peripheral interface circuit) 13 and 15, respectively. Each peripheral interface circuit can contain several (for example four) line circuits which provide four wire pairs, that is to say four push and ring lines (tip and ring lines) to the Centrex system. Peripheral interface circuitry 13 and 15 may be digital network interface circuitry sold by Mitel Corporation under product number MT8972B and described in the Mitel Digital Communications Handbook, which description is incorporated herein by reference.

The peripheral interface circuits connect to the time-divided input and output lines of the time and location division switch 17 , which is referred to below as the DX switch. This switch is described in U.S. Patent 4,510,597, issued April 9, 1985, to inventor Conrad Lewis, which patent is incorporated herein by reference. A DX switch that can be used in element 17 is sold by Mitel Corporation as product type MT8980D or product type MT8981 D, which are also described in the above-mentioned manual, again the description of which is incorporated herein by reference. In a successful prototype of the invention, the DX switch 17 has eight time-divided inputs and eight output lines (connections), six of which were each connected to corresponding peripheral interface circuits, as shown in FIG. 2. The remaining two input and output connections were assigned to a common controller.

Forty-eight ports were provided with a maximum capacity of 192 64 Kbps channels (sixty four Kbit per second channels), providing 12 Mbps bandwidth (megabits per second). The bandwidth allocation was determined with sixteen channels that were assigned to each peripheral interface slot or slot. The six peripheral links (each including an input and output line of the DX switch 17 ) are distributed over the forty-eight ports, with different frame pulses that are sent to a group of twenty-four to split the bandwidth in half . This allows twenty-four ports to use the entire 12 Mbps of bandwidth, or 2 Mbps per shelf, if necessary.

As already mentioned above, the remaining two input and output lines of the DX switch 17 are assigned to a common controller. An input line and an output line of the DX switch are connected to an HDLC circuit 19 (HDLC = high level data link control), and an input line and an output line of the DX switch are connected to a digital signal processor circuit DSP 21 . An ASIC digital signal processor 21 generates signals and decodes signals under the control of the microprocessor 29 . The ASIC 23 is also connected to the HDLC circuit 19 and to one of the common control lines of the DX switch 17 . Inputs from the peripheral interface circuits are connected to the ASIC 23 and the phase lock loop 25 (PLL circuit).

The phase locked loop 25 receives timing information from the interface circuits 13 which receive digital signals from the lines 3 and provides synchronization signals to the ASIC 23 for detection by the microprocessor 29 . The microprocessor 29 can thus synchronize outgoing signals with these detected network signals.

Data and address buses 27 are connected to the ASIC 23 . A microprocessor 29 , preferably the 68000 type, available from Motorola, inc. is available, the random access memory 31 (memory with free (read / write) access) and the ROM 11 are connected to the bus or the bus line 27 . The ROM 11 is connected to the bus line via an externally accessible connection. The ROM 11 contains the programs which the microprocessor 29 accesses in a well known manner to control the operation of the DX switch 17 , the digital signal processor 21 and the ASIC 23 . Unless otherwise identified, the ROM 11 contains a correlation list of centrex lines to the associated or specific subscriber lines.

The circuit operates as follows. Suppose an incoming call from the Centrex system is on line 3 . The line circuit in the PIC 13 receives a ringing signal which is detected and a signal that there is a ringing is sent through the DX switch 17 . The microprocessor 29 , which reads the DX switch 17 , recognizes that a ring signal has been received on a specific line, accesses a program in the ROM 11 and then sends the signal via the ASIC 23 , which decodes this signal, and sends a command signal to the DX switch 17 over the common control line to the peripheral interface circuit 13 to send a local ringing control signal from the DSP 21 to the particular selected telephone set which is on one of the lines 7 for the input line 3 via its associated one Interface circuit 15 is connected.

While other telephone devices or telephone sets can be used, the Within the scope of the present disclosure it is assumed that the telephone set used is a MITEL® SUPERSET 420® is.

If the subscriber reacts and picks up the handset, this is detected in the associated line interface circuit 15 , which sends a dependent signal to the HDLC 19 , which encodes it and sends a signal to the microprocessor 29 . The microprocessor 29 accesses a program in the ROM 11 and sends a control signal to the telephone set, which signal is decoded in the HDLC 23 and sent via the control input of the DX switch 17 , via the associated peripheral interface 15 and the line 7 to turn on the microphone and earphones (speakers) of the telephone set. The microprocessor 29 also sends a message to the peripheral interface 13 belonging to the input line 3 to close the loop to the centrex system. This causes the ringing signal to stop on the centrex line.

The microprocessor 29 then instructs the DX switch 17 to switch a two-way voice channel between the input line 3 and the called line 7 . A voice or voice or data communication with a low data speed can now take place.

If a subscriber wants to use a feature or a property (service) during the call, he presses a feature key or a softkey on his telephone device. The line 7 is monitored by the interface circuit 15 and, in the manner just described, the interface circuit 15 sends a signal to the HDLC 19 after receipt of the contact closure or switch closure of the feature key or the softkey or after receipt of another signal, which reflects the actuation of the feature key and the HDLC translates this into code that is understood by the microprocessor 29 . The microprocessor then determines the appropriate action or response.

For example, if a line hold or transfer or transfer of the call is desired, both of which can be accomplished by the Centrex system, the subscriber presses a hold or transfer button on his telephone set. Since the switch closure of the key of the telephone set is not likely to be the signal expected by the Centrex system, since a telephone is used which is not of the Centrex type, the microprocessor which receives a message via the HDLC causes the special feature or function It is desirable that correct signaling be sent to the Centrex system, that is to say a jagged or blinking signal or a special DTMF code. The ROM 11 contains a table of conversion codes which the microprocessor 29 accesses for the specific function desired. For example, if a subscriber presses a button requesting a service that is invoked by a signal that the centrex system is expecting a spike, the microprocessor, when accessing the table, picks up a conversion code that is to instruct that Interface 13 generates or executes a jerking or flashing pulse (flash) (the current through line 3 is briefly interrupted).

The Centrex system then responds by providing the service, for example by placing a stop signal on the line, forwarding the ringing signal on the line etc. If the translation of the feature call command in the ROM 11 is such that the Centrex system 1 requires a DTMF code, thus the microprocessor 29 transmits a message which is converted by the ASIC 23 , DSP 21 to generate the appropriate DTMF (multi-frequency dialing method) tones or signals which are under the control of the microprocessor 29 by the DX switch 17 and in run the output channel, which leads to the interface circuit 13 , which is connected to the Centrex line 3 currently in use.

The microprocessor 29 maintains the path of each call in the RAM 31 . Thus, if the telephone devices connected to lines 7 have a display such as Mitel Corporation's SUPERSET 420®, microprocessor 29 can provide command signals to the telephone device using programs stored in ROM 11 , using the procedure and method described above to provide a visual indication of the status of the call or a visual indication of the number of the call line or any other visual indication for the telephone in use.

The Centrex system sometimes uses special ring sequences or cadences, such as ringing long and three times short, etc., for certain groups of telephone devices or for certain purposes. The microprocessor 29 can detect and decode that particular ringing and can either cause the telephone set to ring in the same order or only ring normally, or can provide a special message on the display of the telephone set or cause the telephone set to do so in a very special way is operated. For example, if a tone signal is received from the centrex system instead of ringing, the microprocessor 29 decodes the tone in a similar manner as described above and provides information to the local telephone set to which it is directed.

The Centrex system can typically provide services such as redialing the same number, redialing on a busy line, speed dialing, etc. The present invention can enable subscribers connected to the present invention to access and provide these services to the Centrex system in its place (yourself) ready. The microprocessor 29 thus accesses programs in the ROM 11 to effect the redialing of numbers which the microprocessor 19 has monitored as already selected and which it has stored in the memory 31 , thereby performing the function of redialing the same number or to re-elect because of a busy subscriber. RAM 31 can also be used to store speed dial numbers (or speed dial numbers) dialed by the subscriber, commanding that they be dialed by closing special speed dial switches on the telephone set. Indeed, by dialing special codes, the subscriber can store speed dial numbers in the Centrex system, or in the circuit we have just described as RAM 31 , or both.

Whether this or other features are provided may depend on which operating programs are stored in the plug-in ROM 11 , which can be purchased by the user to provide different levels of service. The present invention can thus be specially programmed to provide an interface for different forms of the centrex system or to provide different features for different forms of centrex systems of a telephone company by the telephone company on the basis of groups of features.

It is to be understood that the present invention can be modified or expanded to To form interfaces for normal telephone switching systems instead of Centrex systems or in addition to such and with the addition of a switching system that is chosen on Addresses numbers as a PABX or keypad system can be used.

In fact, the interface circuits, since the interface circuits use bus lines can communicate with the rest of the circuit called the control complex can, grouped together with a power supply and from the control complex be separated. Groups of peripheral circuits with associated power supplies can be distributed around or over a building, connected to a communication bus or a bus line that ends in the control complex. This ensures easy expansion system capability and the application or provision of special requirements specific group of devices that are considered.  

It is understood that the illustrated memories RAM 31 , ROM 11 can be used in various forms. For example, the ROM 11 can carry all of the normal operations and control programs for normal properties for the microprocessor 29 and can be permanently connected to the bus 27 while an auxiliary cassette or auxiliary cassette (not shown) containing special control programs for special properties is inserted into the bus line 27 can be inserted. Optionally, the ROM 11 can carry the normal operating programs for the microprocessor 29 while a memory cartridge can be inserted to hold programs for special features and an additional application module can be added which contains programs which are specially designed for a special installation are.

People who understand the present invention can now consider other structures and Easily present embodiments or variations of the above embodiments. Alles however, these fall within the scope of the appended claims and are considered part of the viewed present invention.

Claims (10)

1. System for the interface linking (interface formation) of telephone devices with a Centrex system, with:

• a) peripheral circuits for the interface linking of telephone lines which are connected to telephone devices and centrex lines,
• b) a handling part for the device, which is connected to the peripheral circuit to connect individual telephone lines and individual centrex lines,
• c) wherein the handling part for the device comprises means for translating line and control signals received from the telephone sets into line and control signals of a type recognizable by the Centrex system, whereby a Centrex call can be continued, such as or as if it is provided by the Centrex system.

2. The system of claim 1, wherein each telephone set is a selected one Centrex line is clearly assigned and can be connected to it. 3. The system of claim 1, wherein the handling part for the device is still out a device exists for the translation of line and / or control signals, which are received by the telephone devices and for providing Services or service features of the telephone devices in addition to the Features or instead of the features provided by the Centrex system. 4. System according to claim 1, 2 or 3, wherein the handling part of the device a device for translating line and / or control signals, which of received by the Centrex system and for which, in response to the signals, Providing services for telephone devices that are not otherwise provided by the Telephone devices could be handled. 5. System according to claim 1, 2 or 3, wherein the handling part of the device a device for translating line and / or control signals, which are received by the Centrex system and, in response to the signals, for the provision of services for the telephone sets, these services represent an addition to the services provided by the Centrex system.   6. System according to claim 1, 2 or 3, in which the handling part of the device a device for translating line and / or control signals, which are received by the Centrex system and ready to be deployed in response to the signals, of services or features for the telephone sets, which are those of the Replace Centrexsystem provided service functions. 7. A method of providing telephone services, the method comprising: the interface connection of (interface formation for) telephone lines connected to Telephone devices are connected, using centrex lines, translating line and Control signals received on the telephone lines from the telephone sets in line and control signals of types by a Centrex system are recognizable, and feeding the translated signals to the centrex lines, whereby a centrex call can be made as if it were from the centrex system provided. 8. The method according to claim 7, with the step of that of the line and control signals selected signals are recognized and that services for the telephone equipment are provided, which are an addition to those provided by the Centrex system Form services or their replacement. 9. The method of claim 7 including means for translating Line or control signals received by the Centrex system and, under Responding to the signals, providing services to the telephone devices that in addition to those provided by the Centrex system. 10. The method of claim 7 including means for translating Line or control signals received from the Centrex system and, in response to providing services for the telephone sets, that replace those provided by the Centrex system.